description |
---|
State component governing redistribution of cryptoassets. |
The outcome of a state is the part which dictates where funds are disbursed to once the channel has finalized.
Nitro protocol uses the L2 exit format, which is designed as standard for supporting a multitude of token types.
!!! tip
At the current time, Nitro supports native (e.g. ETH) and ERC20 tokens.
An Outcome
is an array of SingleAssetExits
, each specifying:
- an
asset
- optional
assetMetadata
- an ordered list of
allocations
The optional assetMetadata
is used only by more exotic asset types, and is zero-ed out for native and ERC20 assets.
An allocation
is
- a
destination
and anamount
- an
allocationType
identifier - optional
metadata
The allocationType
identifier is usually set to 0, meaning "simple".
Simple allocations do not have any metadata
, and allow for funds to be moved on-chain using the transfer
method. See the section on defunding.
When allocationType
is set to guarantee
, funds cannot be transferred in the usual way. Instead, they may be moved to another channel on chain using the reclaim
method. This is explained further in the section on virtual channels. See the section on defunding.
The metadata
is an encoding of the following struct:
struct Guarantee {
bytes32 left;
bytes32 right;
}
where left
and right
correspond to channel participants.
A destination
is 32 byte identifier which may either denote a channel ID or a so-called "external destination" (a 20 byte Ethereum address left-padded with zeros).
Putting these elements together, a simple outcome such as "5 ETH to Alice, 5 ETH to Bob" is expressed like this:
=== "Typescript"
```ts
import {
Exit,
SingleAssetExit,
NullAssetMetadata,
} from "@statechannels/exit-format";
const ethExit: SingleAssetExit = {
asset: "0x0", // this implies the native token (e.g. ETH)
assetMetadata: NullAssetMetadata, // Intentionally left blank
allocations: [
{
destination: "0x00000000000000000000000096f7123E3A80C9813eF50213ADEd0e4511CB820f", // Alice
amount: "0x05",
allocationType: AllocationType.simple, // a regular ETH transfer
metadata: "0x",
},
{
destination: "0x0000000000000000000000000737369d5F8525D039038Da1EdBAC4C4f161b949", // Bob
amount: "0x05",
allocationType: AllocationType.simple, // a regular ETH transfer
metadata: "0x",
},
],
};
const exit = [ethExit];
```
=== "Go"
```Go
import (
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/statechannels/go-nitro/channel/state/outcome"
"github.com/statechannels/go-nitro/types"
)
var ethExit = outcome.SingleAssetExit{
Allocations: outcome.Allocations{
outcome.Allocation{
Destination: types.Destination(common.HexToHash("0x00000000000000000000000096f7123E3A80C9813eF50213ADEd0e4511CB820f")), // Alice
Amount: big.NewInt(5),
// Other fields implicitly zero-ed out
},
outcome.Allocation{
Destination: types.Destination(common.HexToHash("0x0000000000000000000000000737369d5F8525D039038Da1EdBAC4C4f161b949")), // Bob
Amount: big.NewInt(5),
// Other fields implicitly zero-ed out
},
},
}
var exit = outcome.Exit{{ethExit}}
```